The axles of railway vehicles are supported by bearings positioned in axleboxes, and for ascertaining the conditions of the bearings, and also of other parameters affecting the operation of the railway vehicle, it is required to monitor the conditions of bearings, wheels and other parameters it necessary to check these conditions regularly. Earlier such controls have been made with predetermined maintenance intervals.
In EP 1 159 182 B1 has been proposed a railway axle hub unit equipped with sensor means for detecting vibration in vertical direction, and/or in horizontal direction, and/or bearing temperature, and being mounted onto a stationary non-rotating support element, such as a metallic sealing insert.